Using v-model with a prop on VUE.JS

Answer is from https://github.com/vuejs/vue/issues/7434

Props are read-only, but you are trying to change its value with v-model. In this case, if you change the input value, the prop is not modified and the value is restored on the next update.

Use a data property or a computed setter instead:

computed: {
  propModel: {
    get () { return this.prop },
    set (value) { this.$emit('update:prop', value) },
  },
},

https://v2.vuejs.org/v2/guide/computed.html#Computed-Setter